The present invention relates to a new and improved construction of a forced commutation static power or current converter arrangement in a reverse voltage free circuit configuration.
In its more specific aspects, the forced commutation power or current converter arrangement in reverse voltage free circuit configuration comprises a commutation circuit, composed of controllable current converter valves arranged in parallel opposition or antiparallel connection, a commutator capacitor and a commutator reactance coil or choke, a load circuit composed of controllable current converter valves, non-controllable current converter valves arranged in parallel opposition thereto and reactance coils or chokes. Further, there are provided two capacitors arranged between positive and negative d.c.-voltage infeed or supply. The circuit can be employed, for instance, for producing an alternating-current voltage from a direct-current voltage or for producing an alternating-current voltage from an alternating-current voltage of a different frequency.
A typical example of a forced commutation current converter arrangement in reverse voltage free circuit configuration is known to the art from ETZ-A, Bd. 90 (1969), H. 14, pages 353-357 in the article of J. Brenneisen and A. Schonung, entitled "Bestimmungsgroossen des selbstgefuhrten Stromrichters in sperrspannungsfreier Schaltung bei Steuerung nach dem Unterschwingungsverfahren". For describing such type arrangement reference is also made to the article of H. W. van den Boom and E. Kohlhuber, entitled "Beanspruchung von Thyristroen in Wechselrichterschaltungen", VDE-Buchreihe, Bd. 11 "Energieelektronik und geregelte elektrische Antriebe", pages 135-150, VDE-Verlag Berlin 1966.
With such current converters, during operation, there disadvantageously can arise unsymmetrical shifting of the commutation processes. Consequently, the commutation circuit must be overdimensioned. In unfavorable situtions, by virtue of such unsymmetry in the commutation current, there can prevail an operational disturbance in the current converter.